Geo-fencing (Geo-fencing) is a new application of a location based service (Location Based Service, LBS). Specifically, in the application, a virtual fence may be used to form a virtual geographical boundary on an electronic map of a portable electronic device (such as a mobile phone). The portable electronic device may give a notification or a reminder when the portable electronic device enters or leaves a specific geographical area related to the virtual geographical boundary, or moves in the specific geographical area.
For example, the portable electronic device may receive user settings. A geo-fence is set in a corresponding location (such as a gas station, a bank, a supermarket, or a scenic spot) on the electronic map of the portable electronic device, and a notification or a reminder is given to a user when the portable electronic device approaches, enters, or leaves the geo-fence.
However, to reduce power consumption of the portable electronic device, frequency of sampling performed by the portable electronic device on geographical location coordinates of the portable electronic device cannot be excessively high. In this case, when the portable electronic device fast goes through the geo-fence, it is quite possible that the portable electronic device does not perform, within the geo-fence or at a point near the geo-fence, sampling on geographical location coordinates of the portable electronic device, and the portable electronic device does not give a reminder about the geo-fence to a user. As a result, the geo-fencing application cannot work properly.